3GPP LTE系统——背景、原理、系统组成和关键技术.ppt

LTE 标准和技术 Generic Frame structure Available Downlink Bandwidth is Divided into Physical Resource Blocks [source: 3GPP TR 25.814] LTE Reference Signals are Interspersed Among Resource Elements LTE 标准和技术 上行资源块分配 be consecutive in the frequency domain inter-slot frequency hopping b (i) = (b(i) + c(i))mod 2 加扰 scrambling sequence c(i) shall be initialised with cinit = nRNTI ? 2 + ?ns 2? ? 29 + N ID sets, each corresponding to one SC-FDMA symbol M scPUSCH = M RB M scPUSCH ?1 2πik ∑ 1 z(l ? M scPUSCH + k ) = d (l ? M scPUSCH + i)e ? N RB 上行物理层信号处理示例 LTE 标准和技术 上行业务共享信道信号处理 LTE 标准和技术 ~ cell 14 at the start of each subframe 调制映射 预编码 PUSCH UL sc PUSCH ? j M scPUSCH M PUSCH i =0 k = 0,..., M scPUSCH ? 1 l = 0,..., M symb M scPUSCH ? 1 resulting in a block of complex-valued symbols z(0),..., z(M symb ? 1) ∑ c(4Nsymb ? ns + 4l + i) ? 2i 上行控制信道 LTE 标准和技术 PUCCH is never transmitted simultaneously with the PUSCH from the same UE All PUCCH formats use a cyclic shift of a sequence in each symbol used to derive the cyclic shift for the different PUCCH formats varies with the symbol number and the slot number ncscell (ns , l )is UL 3 i =0 ncscell (ns , l ) = 参考信令 LTE 标准和技术 Physical Uplink Control Channel (PUCCH) 上行链路支持两种参考信令 Demodulation reference signal, associated with transmission of PUSCH or PUCCH ? reference symbol on 4th SC-FDMA symbol Sounding reference signal, not associated with transmission of PUSCH or PUCCH ? uplink channel-quality estimation for better scheduling decisions ? position tbd 随机接入信道 LTE 标准和技术 RACH Bandwidth 1.08 MHz (72 subcarriers) Uplink Random Access LTE 标准和技术 Preamble (6 bit) carries random ID, and possibly cause or pathloss indications Response on DL-SCH: addressed to RA-RNTI on PDCCH; conveys preamble identifier, timing alignment information, in